DDESONN vs Keras — 1000-Seed Summary — Heart Failure

Overview

This vignette shows DDESONN results across 1000 seeds (two 500-seed runs) and compares them with a Keras parity run compiled in an Excel workbook.

Where the demo data lives

The four RDS artifacts included with the package are under:

inst/extdata/heart_failure_runs/
│
├─ run1/
│   ├─ SingleRun_Train_Acc_Val_Metrics_500_seeds_20251025.rds
│   └─ SingleRun_Test_Metrics_500_seeds_20251025.rds
│
└─ run2/
    ├─ SingleRun_Train_Acc_Val_Metrics_500_seeds_20251026.rds
    └─ SingleRun_Test_Metrics_500_seeds_20251026.rds

Each folder represents one 500-seed single-run performed locally; together they form the 1000-seed composite.

Motivation and comparison philosophy

This vignette addresses a focused research question:

Can a fully R-native, from-first-principles neural network implementation achieve competitive statistical stability against an established deep-learning framework under repeated randomized initialization?

The comparison to Keras serves as a reference benchmark, not as an implementation template. DDESONN was built independently from scratch and was not derived from or based on Keras source code. Aside from a brief high-level review to understand benchmarking conventions, all implementation and architectural decisions were made independently.

The objective of the 1000-seed experiment is not to highlight a single favorable run, but to evaluate distributional behavior across seeds. In this context, “competitive” refers to:

The comparison evaluates implementation correctness, training stability, and reproducibility under stress — not code replication or framework mirroring.

Load DDESONN runs and build the summary

suppressPackageStartupMessages({
  library(dplyr)
  library(tibble)
})

if (!requireNamespace("DDESONN", quietly = TRUE)) {
  message("DDESONN not installed in this build session; skipping evaluation.")
  knitr::opts_chunk$set(eval = FALSE)
}

.vtbl <- function(x, title = NULL, ...) {
  get("ddesonn_viewTables", envir = asNamespace("DDESONN"))(x, title = title, ...)
}

heart_failure_root <- system.file("extdata", "heart_failure_runs", package = "DDESONN")

if (!nzchar(heart_failure_root)) {
  # fallback when building vignettes from SOURCE (package not installed yet)
  heart_failure_root <- file.path("..", "inst", "extdata", "heart_failure_runs")
}

stopifnot(dir.exists(heart_failure_root))

train_run1_path <- file.path(
  heart_failure_root, "run1",
  "SingleRun_Train_Acc_Val_Metrics_500_seeds_20251025.rds"
)
test_run1_path <- file.path(
  heart_failure_root, "run1",
  "SingleRun_Test_Metrics_500_seeds_20251025.rds"
)
train_run2_path <- file.path(
  heart_failure_root, "run2",
  "SingleRun_Train_Acc_Val_Metrics_500_seeds_20251026.rds"
)
test_run2_path <- file.path(
  heart_failure_root, "run2",
  "SingleRun_Test_Metrics_500_seeds_20251026.rds"
)

# Ensure required files exist
stopifnot(
  file.exists(train_run1_path),
  file.exists(test_run1_path),
  file.exists(train_run2_path),
  file.exists(test_run2_path)
)

train_run1 <- readRDS(train_run1_path)
test_run1  <- readRDS(test_run1_path)
train_run2 <- readRDS(train_run2_path)
test_run2  <- readRDS(test_run2_path)

train_all <- dplyr::bind_rows(train_run1, train_run2)
test_all  <- dplyr::bind_rows(test_run1,  test_run2)

train_seed <- train_all %>%
  group_by(seed) %>%
  slice_max(order_by = best_val_acc, n = 1, with_ties = FALSE) %>%
  ungroup() %>%
  transmute(
    seed, 
    train_acc = best_train_acc,
    val_acc   = best_val_acc
  )

test_seed <- test_all %>%
  group_by(seed) %>%
  slice_max(order_by = accuracy, n = 1, with_ties = FALSE) %>%
  ungroup() %>%
  transmute(
    seed,
    test_acc = accuracy
  )

merged <- inner_join(train_seed, test_seed, by = "seed") %>%
  arrange(seed)

summarize_column <- function(x) {
  pct <- function(p) stats::quantile(x, probs = p, names = FALSE, type = 7)
  data.frame(
    count = length(x),
    mean  = mean(x),
    std   = sd(x),
    min   = min(x),
    `25%` = pct(0.25),
    `50%` = pct(0.50),
    `75%` = pct(0.75),
    max   = max(x),
    check.names = FALSE
  )
}

summary_train <- summarize_column(merged$train_acc)
summary_val   <- summarize_column(merged$val_acc)
summary_test  <- summarize_column(merged$test_acc)

summary_all <- data.frame(
  stat = c("count","mean","std","min","25%","50%","75%","max"),
  train_acc = unlist(summary_train[1,]),
  val_acc   = unlist(summary_val[1,]),
  test_acc  = unlist(summary_test[1,]),
  check.names = FALSE
)

round4 <- function(x) if (is.numeric(x)) round(x, 4) else x
pretty_summary <- as.data.frame(lapply(summary_all, round4))

.vtbl(pretty_summary, title = "DDESONN — 1000-seed summary (train/val/test)")
#> <table>
#>  <thead>
#>   <tr>
#>    <th style="text-align:left;"> stat </th>
#>    <th style="text-align:right;"> train_acc </th>
#>    <th style="text-align:right;"> val_acc </th>
#>    <th style="text-align:right;"> test_acc </th>
#>   </tr>
#>  </thead>
#> <tbody>
#>   <tr>
#>    <td style="text-align:left;"> count </td>
#>    <td style="text-align:right;"> 1000.0000 </td>
#>    <td style="text-align:right;"> 1000.0000 </td>
#>    <td style="text-align:right;"> 1000.0000 </td>
#>   </tr>
#>   <tr>
#>    <td style="text-align:left;"> mean </td>
#>    <td style="text-align:right;"> 0.9928 </td>
#>    <td style="text-align:right;"> 0.9992 </td>
#>    <td style="text-align:right;"> 0.9992 </td>
#>   </tr>
#>   <tr>
#>    <td style="text-align:left;"> std </td>
#>    <td style="text-align:right;"> 0.0014 </td>
#>    <td style="text-align:right;"> 0.0013 </td>
#>    <td style="text-align:right;"> 0.0013 </td>
#>   </tr>
#>   <tr>
#>    <td style="text-align:left;"> min </td>
#>    <td style="text-align:right;"> 0.9854 </td>
#>    <td style="text-align:right;"> 0.9893 </td>
#>    <td style="text-align:right;"> 0.9920 </td>
#>   </tr>
#>   <tr>
#>    <td style="text-align:left;"> 25% </td>
#>    <td style="text-align:right;"> 0.9920 </td>
#>    <td style="text-align:right;"> 0.9987 </td>
#>    <td style="text-align:right;"> 0.9987 </td>
#>   </tr>
#>   <tr>
#>    <td style="text-align:left;"> 50% </td>
#>    <td style="text-align:right;"> 0.9929 </td>
#>    <td style="text-align:right;"> 1.0000 </td>
#>    <td style="text-align:right;"> 1.0000 </td>
#>   </tr>
#>   <tr>
#>    <td style="text-align:left;"> 75% </td>
#>    <td style="text-align:right;"> 0.9937 </td>
#>    <td style="text-align:right;"> 1.0000 </td>
#>    <td style="text-align:right;"> 1.0000 </td>
#>   </tr>
#>   <tr>
#>    <td style="text-align:left;"> max </td>
#>    <td style="text-align:right;"> 0.9963 </td>
#>    <td style="text-align:right;"> 1.0000 </td>
#>    <td style="text-align:right;"> 1.0000 </td>
#>   </tr>
#> </tbody>
#> </table>

Keras parity (Excel, Sheet 2)

Keras parity results are stored in an Excel workbook included with the package under:

inst/extdata/vsKeras/1000SEEDSRESULTSvsKeras/1000seedsKeras.xlsx

The file is accessed programmatically using system.file() to ensure CRAN-safe, cross-platform installation paths.

if (!requireNamespace("readxl", quietly = TRUE)) {
  message("Skipping keras-summary chunk: 'readxl' not installed.")
} else {
  keras_path <- system.file(
    "extdata", "vsKeras", "1000SEEDSRESULTSvsKeras", "1000seedsKeras.xlsx",
    package = "DDESONN"
  )

  if (nzchar(keras_path) && file.exists(keras_path)) {
    keras_stats <- readxl::read_excel(keras_path, sheet = 2)
    .vtbl(keras_stats, title = "Keras — 1000-seed summary (Sheet 2)")
  } else {
    cat("Keras Excel not found in installed package.\n")
  }
}
#> Keras Excel not found in installed package.

Reproducibility notes

Distributed execution (scaling note)

The results shown here were computed locally.

For large-scale experiments (hundreds to thousands of seeds), DDESONN can be executed in distributed environments to significantly reduce wall-clock time. Distributed tooling and development-stage orchestration scripts are maintained in the GitHub repository and intentionally excluded from the CRAN build so that this vignette remains focused on validated results and methodology.